Short message service interworking

ABSTRACT

Various communication systems may benefit from suitable interworking. For example, certain fifth generation short message service systems may benefit from interworking with long term evolution short message service deployments in a visited public land mobile network. A method can include receiving, at a network element, an attach request from a user equipment. The method can also include using an internal policy to find a short message service function that resides at the network element. The method can further include using an address of the short message service function for providing short message service to the user equipment.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to and claims the benefit and priority ofU.S. Provisional Patent Application No. 62/444,617, filed Jan. 10, 2017,the entirety of which is hereby incorporated herein by reference.

BACKGROUND Field

Various communication systems may benefit from suitable interworking.For example, certain fifth generation short message service systems maybenefit from interworking with long term evolution short message servicedeployments in a visited public land mobile network.

Description of the Related Art

Fifth generation (5G) is a new generation of radio systems and networkarchitecture delivering extreme broadband, as well as ultra-robust, lowlatency connectivity and massive machine-to-machine connectivity for theInternet of Things (IoT) to enable the programmable world.

5G may, for example, aim to provide massive broadband that deliversgigabytes of bandwidth in uplink and downlink per second on demand. 5Gmay also provide critical machine-type communication that allows for theimmediate, or with extreme low end to end (e2e) latency, synchronouseye-hand feedback that permits remote control of robots and cars.Furthermore, 5G may also provide massive machine-type communication thatconnects billions of sensors and machines.

The biggest difference between 4G and 5G design requirements may be thediversity of use-cases that 5G networks may need to support as comparedto 4G networks. 4G networks were primarily designed for the singleuse-case of delivering high speed mobile broadband.

5G may not only be a new radio access technology (RAT) family. The 5Garchitecture may expand to multiple dimensions by providing a commoncore for multiple radio technologies (for example, cellular, Wi-Fi, andfixed), multiple service (for example, IoT, mobile broadband, lowlatency-high reliability) and multiple network and service operators.

FIG. 1 illustrates an example of a short message service (SMS) functionin a fifth generation core network. The 5G core network may provide SMSover non-access stratum (NAS) to a user equipment (UE). In FIG. 1, the“SMS Function”, regardless of it being implemented by the mobilitymanagement entity (MME) or mobile switching center (MSC) server may needto provide relay protocol (RP) layer and control protocol (CP) layerprotocol and also other adjunct functionality like charging data record(CDR) and lawful intercept (LI), among others. For 5G, AMF may need tointeract with some kind of “SMS Function” in order to provide SMSservice to UE.

SUMMARY

According to a first embodiment, a method can include receiving, at anetwork element, an attach request from a user equipment. The method canalso include using an internal policy to find a short message servicefunction that resides at the network element. The method can furtherinclude using an address of the short message service function forproviding short message service to the user equipment.

In a variant, the network element can be a mobile switching center.

In a variant, the address of the short message service function is usedinstead of an address of a home short message service function of theuser equipment.

According to a second embodiment, a method can include receiving, at ahome location register, a location update that includes an address. Themethod can also include determining whether the location updatecorresponds to a first domain or a second domain. The method can furtherinclude separately handling the location update based on whether thelocation update corresponds to the first domain or the second domain.

In a variant, the first domain can correspond to a short message servicefunction.

In a variant, the second domain can correspond to a 2/3G/LTE MSC.

In a variant, separately handling can include sending a cancel locationwith respect to the address only when a new location update is receivedfor a same domain as the address.

In a variant, the determining can include comparing the address to apreviously configured short message service function address.

According to third and fourth embodiments, an apparatus can includemeans for performing the method according to the first and secondembodiments respectively, in any of their variants.

According to fifth and sixth embodiments, an apparatus can include atleast one processor and at least one memory including computer programcode. The at least one memory and the computer program code can beconfigured to, with the at least one processor, cause the apparatus atleast to perform the method according to the first and secondembodiments respectively, in any of their variants.

According to seventh and eighth embodiments, a computer program productmay encode instructions for performing a process including the methodaccording to the first and second embodiments respectively, in any oftheir variants.

According to ninth and tenth embodiments, a non-transitory computerreadable medium may encode instructions that, when executed in hardware,perform a process including the method according to the first and secondembodiments respectively, in any of their variants.

According to eleventh and twelfth embodiments, a system may include atleast one apparatus according to the third or fifth embodiments incommunication with at least one apparatus according to the fourth orsixth embodiments, respectively in any of their variants.

BRIEF DESCRIPTION OF THE DRAWINGS

For proper understanding of the invention, reference should be made tothe accompanying drawings, wherein:

FIG. 1 illustrates an example of a short message service function in afifth generation core network.

FIG. 2 illustrates a general representation of short message servicearchitecture in fifth generation core network without reliance oncircuit switched identities.

FIG. 3 illustrates an SMS function proxy for SMS function selection.

FIG. 4 illustrates SMS over NAS architecture used for 2/3G and LTEaccess.

FIG. 5 illustrates a typical VPLMN deployment with 5G and LTE for SMS.

FIG. 6 illustrates an option involving a local SMS function, accordingto certain embodiments.

FIG. 7 illustrates circuit switched location update separation intomultiple domains, according to certain embodiments.

FIG. 8 illustrates a home location register marking an update, accordingto certain embodiments.

FIG. 9 illustrates mobile terminated SMS delivery, according to certainembodiments.

FIG. 10 illustrates a method according to certain embodiments.

FIG. 11 illustrates a further method according to certain embodiments.

FIG. 12 illustrates a system according to certain embodiments.

DETAILED DESCRIPTION

FIG. 2 illustrates a short message service architecture without relianceon circuit switched identities. Thus, FIG. 2 provides an architecturefor SMS without any dependency on circuit switched (CS) identities suchas temporary mobile subscriber identity (TMSI) or local area identity(LAI). Rather the illustrated approach can use a temporary identifier(ID) allocated by an access management function (AMF) to contain apointer to the SMS function in order to enable selection of SMSfunction.

During initial registration, UE can include a request for SMS service.Based on the UE's request, the AMF can assign an SMS function and canensure that the UE has a subscription to obtain an SMS service.Subscription check for SMS for the given UE can be performed either bythe AMF or by a service management function (SMF). As part of responseto initial registration, the AMF can assign a temporary ID-1 for the UEfor subscriber confidentiality and this includes also AMF identifier (ifit wishes to remain its serving function until it receives the nextrequest for a given UE). Along with the temporary ID-1, AMF eitherencodes the pointer to SMS function with temporary ID-1 or createsanother temporary ID-2 to point to the SMS function.

When the UE sends a subsequent non-access stratum (NAS) message to theAMF, the UE can include the allocated temporary identifiers. Based onthe AMF identifier within the temporary ID-1, the radio access network(RAN) can route the message to the appropriate AMF. Similarly, eitherbased on SMS function within temporary ID-1 or temporary ID-2, the AMFcan determine the SMS function for the given UE.

As an alternative to encoding SMS Function ID within the temporary IDassigned to the UE, AMF and SMS function can have independentidentifiers over Nx to identify each other—AMF can keep track of an SMSFunction ID and SMS function can keep track of an AMF ID. When a new AMFis selected for a given UE, the old AMF can provide the SMS function IDas part of the context request procedure.

When the UE needs to send an SMS to the network, the UE can encapsulatethe SMS within the NAS transport message. This NAS transport message canbe routed to the SMS function which can eventually route the SMS to theSMS center (SMSC).

When the SMS function needs to send an SMS to the UE, the SMSC canforwards the SMS via the SMS function/AMF, which can eventuallyencapsulate the SMS within the NAS transport message. The encapsulatedSMS message can be routed to the UE.

FIG. 3 illustrates an SMS function proxy for SMS function selection. Oneway to realize the above principle is that the AMF can contain an SMSfunction proxy as shown in FIG. 3. This SMS function proxy can be usedto analyze the temporary ID-1 (or ID-2) to route to the proper SMSfunction. In the FIG. 3, a temporary ID (A) may point to an internal SMSfunction that has an external interface (e.g., SGd) towardIWMSC/SMS-GMSC/SMS Router, and another temporary ID (B) may point to anexternal SMS function via Nx.

SMS over NAS may be required for 5G. NAS can include a set of protocolsused to convey non-radio signaling between the user equipment and thecore network (CN). In LTE, SMS over NAS can be supported either by SGsinterface with an MSC server, or with an “SMS in MME” option, asdescribed at 3GPP TS 23.272. In the roaming scenario, a visited publicland mobile network (VPLMN) may have to have an access to a local MSCserver or implement the “SMS in MME option” in order to support SMS overNAS feature.

FIG. 4 illustrates SMS over NAS architecture used for 2/3G and LTEaccess. In FIG. 4, the interfaces MAP-D, MAP-E, and SGs can representthe interfaces needed for “SMS over SGs”, while the interfaces SGd, S6aand S6C can represent the interfaces needed for an “SMS in MME” option.

5G architecture may be built with a common core for multiple radiotechnologies, such as cellular, Wi-Fi, and fixed, and this common coremay allow different type of green field operators to offer 5G services.In a roaming case, the HPLMN may not require that these green fieldoperators can access a local MSC server for providing SMS for theirroaming user. In other words, the HPLMN may not rely on VPLMNcapabilities and service offering in order to offer SMS to their users.

The 5G core network may be capable of providing SMS over NAS to a UEwith home routed model. However, certain embodiments can take intoaccount other possible SMS deployment options in the VPLMN and canresolve some interaction with a home routed model for SMS.

FIG. 5 illustrates a typical VPLMN deployment with 5G and LTE for SMS.In FIG. 5, there is a VPLMN with both 5G and LTE from the same PLMN. Oneissue is that each time the UE moves back and forth between 5G and LTE,the MSC Sever at the VPLMN may perform a location update procedure tothe HLR in the HPLMN via the MAP-D interface. This may create anexcessive signaling load over MAP-D interface

FIG. 6 illustrates an option involving a local SMS function, accordingto certain embodiments. According to one option, labelled Option A forconvenience only and not for limitation, a VPLMN may be allowed toestablish Nx to a local SMS function, which may be the same one that isused for SGs to MME. In other words, a visited AMF can avoid using ahome routed method, but instead a local Nx connection can be usedtowards the SMS function.

FIG. 6 thus illustrates a 5G architecture with a local Nx for supportingSMS over NAS in roaming scenario. With this approach, the VPLMN AMF cantake into account the policy that the MME is using for selecting the SMSfunction. This includes the possibility for multiple CS domains forselection.

In this option, during a UE Attach procedure to 5G, the AMF may not usethe “SMS Function” address given from the UDM, but instead may use aninternal policy to find the “SMS Function” that resides at the same MSCwhich is used for 2/3/LTE. The AMF may need to allocate an LAI thatwould allow the target-MME to select the same MSC server for SGsassociation.

On the UE side, the CS identities including LAI and TMSI received from2/3/LTE can be retained and passed to 5G and vice versa. This passingmay allow the AMF to use the TMSI based NRI as provided by the UE or thesame IMSI hash function to retrieve the “SMS Function” that iscorresponding to the VLR number used at the MME side. Basically, the AMFcan support the same SMS function selection process, as described belowfor MME, in SMS over SGs in order to ensure the same MSC/VLR is selectedwhen UE goes back and forth between LTE and 5G.

Overall, the UE can be configured to carry the LAI and TMSI receivedfrom 5G to LTE and vice versa. Similar VLR configuration data can becarried between the MME and AMF.

Another alternative, designed option B for convenience only and not forlimitation, is to avoid having the HLR send a Map CANCEL Location to theVPLMN MSC when the UE moves back and forth. This may ensure thatseamless interworking between 5GS and EPS can be achieved bydifferentiating them appropriately within the UE and network.

This approach can rely on the following principles. The HLR/HSS/UDM cankeep the location update procedure separate. For example, the locationupdate procedure from an SMS function can be differentiated from the oneperformed by a 2/3G/LTE MSC. The location update procedure from onedomain can be prevented from affect the other domain. Within eachdomain, the HLR/HSS/UDM can follow the existing procedure handlingcancel location. Thus, for example, HLR/HSS can send a Cancel Locationto the OLD MSC when a location update with a new MSC address is receivedbut not when a location update from SMS function for 5G core isreceived.

Another principle is that the UE can carry the CS domain identities,such as LAC/TMSI, from 2/3/LTE and can use them only during access to2/3/LTE. In other words, these CS domain identities may not be used ormodified in the 5G side.

A further principle is that on 5G, the UE may receive identities fromthe SMS function via 5G NAS. This information from the SMS function canbe used to correlate the same SMS function in the HPLMN when the UEmoves from one 5G area to another 5G area, or different AMF are used.Identities from the SMS Function via 5G NAS (if received) may not beused or modified in the 2/3/LTE access.

An additional principle is that when SMS-GMSC retrieves the node addressfor SMS delivery, the HLR/HSS/UDM can return both the current registeredMSC address for 2G/3G/LTE and the SMS function address for 5G. Thismeans the HLR/HSS/UDM can return two nodes for SMS delivery, for over 5Gand 2/3/LTE.

The HLR/HSS/UDM may return the node address(es) in any order ofsequence. For example, the HLR/HSS/UDM can provide the VPLMN MSC numberas a network node number and HPLMN MSC number as additional network nodenumber or the other way around. The node address may or may not besignificant to the SMS-GMSC, as the SMS-GMSC may make any decision as towhere to try first. For example, the SMS-GMSC can select one node fordelivery then retry the other node if the first one fails.

FIG. 7 illustrates circuit switched (CS) location update and SMSFunction for 5G Core separation into multiple domains, according tocertain embodiments. More particularly, FIG. 7 illustrates CS locationupdate separation into 5G SMS Function domain and others (2/3/LTE(CSFB)) domain.

The following procedure shows how the HLR/HSS/UDM can separate the SMSrelated registration into the 2 domains. When the attaches to 5G, theVPLMN AMF can get the HPLMN SMS function address from UDM and the AMFcan perform the Nx registration to that SMS function. The SMS functionthen perform a location update to the HLR/HSS/UDM.

The HLR/HSS/UDM is aware that the address is the SMS function addressfor SMS delivery via 5G access based on the following: the SMS functionaddress can be configured to the HSS/HLR/UDM; the HLR/HSS/UDM checks theSMS function address when the HLR/HSS/UDM receives location updaterequest and, if matched, the HSS/HLR/UDM marks this update as “5G SMSupdate”; all SMS function address that has been marked as “5G SMS” canbe in one domain; and all SMS function with MSC Server address for2G/3G/LTE that has not been marked as “5G SMS MSC” can be in the otherdomain.

FIG. 8 illustrates a home location register marking an update, accordingto certain embodiments. More particularly, FIG. 8 illustratesHLR/HSS/UDM marking an SMS Function as “5G SMS update.”

The location update from one domain may not cause the HLR/HSS/UDM tosend a “cancel location” to the other domain. Now the HSS/HLR/UDM cancontain two SMS delivery addresses, and these two addresses can be sentto an SMS-GMSC when being inquired for send routing information (SRI)for short message (SM). As mentioned above, the HLR/HSS/UDM may returnthe node addresses in any desired sequence, and these can be handled asdesired by the SMS-GMSC. See TS 29.002 and TS 23.040 for ways toretrieve multiple network node numbers using MAP and SMS procedures.

FIG. 9 illustrates mobile terminated SMS delivery, according to certainembodiments. As shown in FIG. 9, at 1, the SC can provide a messagetransfer to the SMS-IWMSC. In response, the SMS-IWMC at 2 can issue asending routing info for short message request to an HSS/HLR. At 3, theSMS-IWMC can receive a routing information for SM response message fromthe HSS/HLR/UDM. The response can include multiple node addresses. TheSMS-IWMSC can forward the mobile terminated short message to a firstnode address selected from the list. If needed, the SMS-IWMSC can retryto the other node address.

On the UE side, the UE may need to retain the TMSI and LAI that it hasreceived earlier from LTE/2/3G, as well as the SMS function identitiesreceived from 5G. In other words, 5G may not overwrite the identities UEreceived from 2/3/LTE (LAC, TMSI) and vice versa. Thus, the UE canmanage these identities independently. This can allow the same MSC orSMS function to be selected when UE switches back and forth betweenRATs.

FIG. 10 illustrates a method according to certain embodiments. Themethod of FIG. 10 can, for example, correspond to option A mentionedabove. The method can include, at 1010, receiving, at a network element,an attach request from a user equipment. The network element can be amobile switching center.

The method can also include, at 1020, using an internal policy to find ashort message service function that resides at the network element. Themethod can further include, at 1030, using an address of the shortmessage service function for providing short message service to the userequipment. For example, the address of the short message servicefunction can be used instead of an address of a home short messageservice function of the user equipment. Compare, for example thearrangement of FIG. 5 with the arrangement of FIG. 6, in which a localSMS function is used instead of an SMS function in the home network.

FIG. 11 illustrates a further method according to certain embodiments.The method of FIG. 11 may, for example, correspond to option B discussedabove.

The method can include, at 1110, receiving, at a home location register,a location update that includes an address. The method can also include,at 1120, determining whether the location update corresponds to a firstdomain or a second domain. More than two domains can be used, ifdesired. The first domain can correspond to a short message servicefunction, whereas the second domain can correspond to a 2/3G/LTE MSC, orvice versa. The determining can include, at 1125, comparing the addressto a previously configured short message service function address.

The method can further include, at 1130, separately handling thelocation update based on whether the location update corresponds to thefirst domain or the second domain. The separately handling can include,at 1140, sending a cancel location with respect to the address only whena new location update is received for a same domain as the address.

FIG. 12 illustrates a system according to certain embodiments of theinvention. In one embodiment, a system may include multiple devices,such as, for example, at least one UE 1210, at least one MSC 1220, whichmay be an SMS-IWMSC, and at least one HLR 1230.

Each of these devices may include at least one processor, respectivelyindicated as 1214, 1224, and 1234. At least one memory can be providedin each device, and indicated as 1215, 1225, and 1235, respectively. Thememory may include computer program instructions or computer codecontained therein. The processors 1214, 1224, and 1234 and memories1215, 1225, and 1235, or a subset thereof, can be configured to providemeans corresponding to the various blocks of FIG. 9.

As shown in FIG. 12, transceivers 1216, 1226, and 1236 can be provided,and each device may also include an antenna, respectively illustrated as1217, 1227, and 1237. Other configurations of these devices, forexample, may be provided. For example, HLR 1230 may be configured forwired communication, in addition to wireless communication, and in sucha case antenna 1237 can illustrate any form of communication hardware,without requiring a conventional antenna.

Transceivers 1216, 1226, and 1236 can each, independently, be atransmitter, a receiver, or both a transmitter and a receiver, or a unitor device that is configured both for transmission and reception.

Processors 1214, 1224, and 1234 can be embodied by any computational ordata processing device, such as a central processing unit (CPU),application specific integrated circuit (ASIC), or comparable device.The processors can be implemented as a single controller, or a pluralityof controllers or processors.

Memories 1215, 1225, and 1235 can independently be any suitable storagedevice, such as a non-transitory computer-readable medium. A hard diskdrive (HDD), random access memory (RAM), flash memory, or other suitablememory can be used. The memories can be combined on a single integratedcircuit as the processor, or may be separate from the one or moreprocessors. Furthermore, the computer program instructions stored in thememory and which may be processed by the processors can be any suitableform of computer program code, for example, a compiled or interpretedcomputer program written in any suitable programming language.

The memory and the computer program instructions can be configured, withthe processor for the particular device, to cause a hardware apparatussuch as UE 1210, MSC 1220, and HLR 1230, to perform any of the processesdescribed herein (see, for example, FIGS. 10 and 11). Therefore, incertain embodiments, a non-transitory computer-readable medium can beencoded with computer instructions that, when executed in hardware,perform a process such as one of the processes described herein.Alternatively, certain embodiments of the invention can be performedentirely in hardware.

Furthermore, although FIG. 12 illustrates a system including a UE, MSC,and HLR, embodiments of the invention may be applicable to otherconfigurations, and configurations involving additional elements. Forexample, not shown, additional UEs may be present, and additional corenetwork elements may be present, as illustrated in FIGS. 1 through 9.

One having ordinary skill in the art will readily understand that theinvention as discussed above may be practiced with steps in a differentorder, and/or with hardware elements in configurations which aredifferent than those which are disclosed. Therefore, although theinvention has been described based upon these preferred embodiments, itwould be apparent to those of skill in the art that certainmodifications, variations, and alternative constructions would beapparent, while remaining within the spirit and scope of the invention.

We claim:
 1. A method, comprising: receiving, at a network element, anattach request from a user equipment; using an internal policy of thenetwork element to find a short message service function that resides atthe network element; and using an address of the short message servicefunction for providing short message service to the user equipment. 2.The method of claim 1, wherein the network element is a mobile switchingcenter.
 3. The method of claim 1, wherein the address of the shortmessage service function is used instead of an address of a home shortmessage service function of the user equipment.
 4. An apparatus,comprising: at least one processor; and at least one memory includingcomputer program code, wherein the at least one memory and the computerprogram code are configured to, with the at least one processor, causethe apparatus at least to receive, at a network element, an attachrequest from a user equipment; use an internal policy of the networkelement to find a short message service function that resides at thenetwork element; and use an address of the short message servicefunction for providing short message service to the user equipment. 5.The apparatus of claim 4, wherein the network element is a mobileswitching center.
 6. The apparatus of claim 4, wherein the address ofthe short message service function is used instead of an address of ahome short message service function of the user equipment.